Lighting system embodying two or more arc discharge devices and ballast therefor



Sept. 18, 1951 MAUERER 2,568,553

LIGHTING SYSTEM EMBODYING TWO OR MORE ARC DISCHARGE DEVICES AND BALLAST-THEREFOR Filed April 15, 1946 2 Sheets-Sheet 1 fnz/enl af" leg 2901i ffauerer EM WWW l 13, 1951 L MAUERER 2,568,553

LIGHTING SYSTEM EMBOI YING TWO OR MORE ARC DISCHARGE DEVICES AND BALLAST THEREFOR Filed April 15, 1946 2 Sheets-Sheet 2 fnveni or leg b0 Mauerer "factor. "-actance transformer having a primary and two Patented Sept. l8, 1951 MORE ARC DISCHARGE DEVICES AND BALLAST THEREFOR Leopold Mauerer, Ghicago,':Ill.,zassignor to;Jeffer- 'son ElectricyCompany, Bellwood, 111., a corporation, of Illinois Application April"15, 1946,-"Serial No.'6'62,136

:5 Claims. 1 This invention-relates to lighting systems embodying two 'or more arc discharge devices, such as fluorescent lamps; and'in particular, to an improved electrical apparatus "for supplying such discharge devices with electrically displaced operating currents, for the purpose of reducing "stroboscopic effect and improving the power'factor.

These supply devices, commonlyca'lledballasts,

"have, in the past, been of two principal types. The 'first-type consists ofthe combination of an "auto transformer which supplies the "necessary =voltage'for striking the arc, together with two reactors, one foreach lamp, a condenser beingconnected in series with onset the reactors to'provide the-current-displacement necessary to reduce stroboscopic-efiect and to correct the power The second typeconsists of ah-igh reloosely coupled secondaries-a condenserbeing connecte'd in-series with one of the'secondaries. The transformer may be either double wound, or "an'auto transformer; and in the latter instance, the total of the output voltage for each secondary circuit is-made up'of the sum of'the primary voltage plus the secondary-voltage.

This-invention relates to the second type of ballast. Such'ballasts have aserious shortcom- "ing in that the leading secondary circuit delivers a distorted or peaked current wave'to-the lamp, which shortens the lamp life and also causes a more "pronounced stroboscopic effect. Further- "more, ballasts of thistype often deliver-an insufficient amount of power to the leading lamp circuit.

The-above mentioned distortion of thecur-rent wave is caused by magnetic saturation'in the laminations of the leading secondary circuit.

The high'fiux density which causes this satura- "tionis not intentionally designed intothe 'transformer, but is the result ofthe unusual phase relations existing in a highreactance transformer operating into a capacitativecircuit. The result of this type of operation is a voltage'across the leading secondary circuit which is considerably in excess of the normalopen circuit voltage for which such transformers are usually designed and dimensioned. If, therefore; according to the *present commercial practice, the'tr-ans'forrner is designedso as to deliver the usual-secondary circuit voltage necessary to' strike-an-arc, and if,

for reasons of economy, the core is designed-so that the flux density-approaches the'saturation point under such open circuit-conditions, then under operating conditions, when the secondary "operating conditions.

' circu-it feedsintoa load circuit" which includes a lamp as well as a condenser, the voltagepand therefore the flux density in the lead-ing second- "ary magnetic circuit, will increase to considerably higher values, which in turn,'wi1l "cause distortion :of thefcurrent wave-shape, due to magneticisat .uration.

"It-is an object-of this invention to "provideaan improved lighting circuit in which "the zarc- 'adischarge devices have a longer life, "andz.in"which the stroboscopic' effect is-reduc'ed and" therpower -factor improved.

Itis .a further obj'ectrof this invention to-::providein a fluorescent lamp system of ithetype :described, a ballast of the high reactanceitransformer type which willnbe'fre'e 'fromx thefshort- *comings outlined above.

I- hav'eifound that these obj ects :ca-nbe attained by providing a lighting systemuinw'vhich the-flux density inthe leading secondary: magnetic "cir- 'cu-it'is substantially the same asthe fluxfidensity *of the lagging secondary magnetic r-circuit under Thus, not onlydo I'achieve uniform intensity of illumination in bothlamps, 'and -improve'd lamp life, but Iiam alsoenabled to improve the current'wave shapein the leading :secondary-circuit,and-with respect .to thersystem -'as :a whole, to reduce stroboscopic effect. andimprove the power factor.

Stillanother object of this invention is to provide an improved ballast for a lighting system :of

this type in-which' the core for 'the-Iea'dingxsecond'ary magnetic-circuit is providedwitha larger 'cross sectional area than the core for-thel aggi-ng :m'agnetic secondary-circuit.

'A-sti-ll 'turther'object is-to provide, in-a system of I this type; an improved "core structure for-the ballastzwhich facilitates the assembly of the elements.

Other objects, features :and improvements will 'become apparent as this description proceeds.

'With reference now to the drawings, in which like reference numerals designate likeiparts- Figulis a sectional elevationoi aballast'em- 1 hodying :my invention Figxz is az'section taken alone 1ine:2"2zof Fig; 1

Fig.3 is a sectional view of a modified form "of ballast;

Fig- 4 isa diagram of the lighting systemasza 'whole; and

Figs. 5 and 6 are diagrams of a modified system. "In Figs-4 the ballast is designated generally by thereference numeral [0, and it comprisesa-pri- -mary-winding'l I; a lead secondary winding-i2,

"and-a lag secondary winding I 3, the-windings being connected in autotransformer relationship. Arc discharge devices, such as fluorescent lamps I6 and II, are provided for each of the secondary circuits, which may be referred to as the lead secondary circuit 24, and the lag secondary circuit 25. The lead secondary circuit 24 includes a condenser I4 which is connected in series with the lead secondary winding I2 and the lamp I6.

To the terminals 22 and 23 of the primary windcuit includes the primary winding II, the secondary winding I3, a conductor I9 connecting the secondary winding to the lamp II, the lam itself,

and a portion of the T-connection 2|.

In operation it will be seen that the lead circuit 24 will be energized by a leading current, due to the preponderance of the capacitative reactance provided by the condenser I4 over the inductive reactance provided by the secondary I2. The lag circuit 25 will be energized by a lagging current, due to the inductive reactance of the secondary I3.

The core of the ballast I0, shown in Fig. 1, comprises a stack of E laminations 30 which are maintained in abutting relationship with an oppos y disposed stack of E laminations 3|. It will be observed that the laminations 30 are of greater width than the laminations 3| The laminations may be maintained in their respective stacks, and in abutting relationship by suitable core clamping means, not shown.

The lead secondary I2 is disposed on the middle leg of the E laminations 30, and the lag secondary I3, together with the primary winding I I,

- the leadsecondary I2 on their respective cores are such that when the stacks of laminations are assembled, the primary is spaced from the lead secondary I2, as shown in Fig. 1. Thus flux leakage paths 34 are provided between these windings, the flux leakage paths, however, providing a path of somewhat greater reluctance than that provided by the magnetic shunts 32.

From an inspection of Fig. 1, it is obvious that the coreof the lead secondary can carry a greater flux than the core of the lag secondary, the parts preferably being proportioned so that the flux density in each part of the core is substantially the same under normal operating conditions. The

" particular arrangement shown, consisting of two abutting stacks of E laminations, makes for simplicity in assembling the transformer, inasmuch as it requires the provision of only two different types of laminations.

In the embodiment of my invention which is herein shown and described, the secondary windings I2 and I3 are preferably proportioned so as .to apply substantially equal voltages to the circuits 24 and under open circuit conditions, that is, before an arc is struck across the lamps. However, after the arc has been struck, and the circuit established, the voltage in the lag circuit 25, including the winding I3, will be lower than the voltage under open circuit conditions, due to the leakage reactance, while the voltage in the lead circuit 24, including the Winding I2, will be greater than the open circuit voltage. Therefore, since the flux is proportional to the voltage, the flux in the lamination stack will be greater than the flux in the corresponding portion of the lamination stack 3|. Due to the increased cross section of the lamination stack 3|], the flux density may be maintained below the saturation point so that the current wave in the lead circuit 24 is not distorted.

Themodified form of ballast 40 shown in Fig.

3, includes a press fit core comprising two stacks of the lamination stack 4|.

of laminations 4| and 42. Stack 4| is formed from laminations stamped in the form of a hollow rectangle and it will be observed that a portion 43 of the lamination stack is of a narrower Width than a portion 44. Shunt portions 45 are integrally stamped with the laminations of stack 4|.

The lamination stack 42 comprises the central leg of the shell type core provided by both stacks, and this stack of laminations has a portion 41 of narrower width and'a portion 48 of greater width. Portions of the lamination stacks 4| and 42 are of complementary shape, so as to provide suitable joints 49 and 50 between the two core stacks,

. the dimensions being such that the parts may be ing I3 are disposed on the narrower portion 41 of the central leg 42, and are embraced by the I narrower portion 43 of the lamination stack 4|,

whereas the lead secondary winding I2 is disposed on the portion 48 of the central leg which is of greater width, and is embraced by the portion 44 The dimensionsare such that an air gap 45 is provided between the shunt portions 45 and-the central leg 42 to provide for the proper reluctance of the leakage path between the lag secondary and the primary.

The lead secondary I2 and the primary II are spaced from each other by a sufficient distance to provide leakage paths 52, similar to the leakage paths 34 of Fig. 1.

The operation of the ballast shown in Fig. 3 is substantially the same as that shown in Figs.

1 and 2. I

In Fig. 5 is shown the diagram of a modified circuit in which the windings of the ballast are connected as a double wound transformer, as contrasted with the autotransformer of Fig. 4.

The reference numerals of the corresponding parts are the same as the reference-numerals used in Fig. 4, with the exception that they are primed. Thus, lead secondary circuit 24' includes secondary winding I2, condenser I4, conductor I8, lamp I6, and portions of connection 2|; whereas, the lag secondary circuit 25'" includes secondary winding I3, conductor I9, lamp I1 and portions of connection 2|.

If desired, one of the secondary windings may be connected in autotransformer relationship with the primary, and the other of the secondary windings may be in the usual transformer relationship.

Both of the circuits shown in Figs. 4 and comprise an instant starting lighting system, that is, one which operates without starters.

However, starting circuits 26 and 21, shunted around the lamps I6 and I1, may be provided if desired, as shown by the dotted lines in Fig. 6.

My invention has been described primarily with reference to lighting systems embodying fluorescent lamps; however, it is obvious that it is applicable to lighting systems embodying other types of gaseous conduction tubes, such as neon tubes, or even to other illuminating devices, such as are lamps which exhibit negative resistance characteristics.

Although only preferred embodiments of my invention have been shown and described herein, it is understood that numerous modifications and changes may be made therein without departing from the spirit of my invention as defined by the appended claims.

I claim:

1. A ballast for a fluorescent lamp system embodying two lamp circuits, said ballast comprising a core having a winding leg and a yoke, a primary winding centrally disposed on said winding leg, a lagging secondary winding disposed on said winding leg at one side of said primary winding, and a leading secondary winding disposed at the other end of said Winding leg, said windings being spaced from each other so as to provide for leakage reactance, that portion of said winding leg on which said leading secondary winding is disposed being of greater cross section than the remainder of said winding leg and that portion of said yoke which is adjacent said leading secondary winding being of greater cross section than the remainder of said yoke in order to compensate for the higher voltage in said leading secondary winding.

2. In a gaseous discharge lamp system having a primary circuit, a leading secondary circuit and a lagging secondary circuit, said primary circuit including a primary winding, said leading secondary circuit including a secondary winding, a condenser and a gaseous discharge lamp, and said lagging secondary circuit including a separate secondary winding and a second gaseous discharge lamp of like characteristics, a core structure for said windings designed to operate at or near saturation and comprising two E-shaped stacks of laminations arranged in abutting relationship to provide a shell type core, one of said stacks of laminations linking said lagging secondary winding and said primary winding, and the other of said stacks of laminations linking said leading secondary winding, said latter stack of laminations having a greater cross sectional area in all portions thereof than the cross sectional area in the corresponding portions of said first mentioned stack of laminations, said primary winding being disposed between said secondary windings in end to end relationship on the central leg of said core, and being spaced therefrom to provide flux leakage paths, and a shunt of magnetic material disposed in that flux leakage path which is between said primary and said lagging secondary windings.

3. In a fluorescent lamp system, a ballast for supplying electrically displaced operating currents to two separately operable fluorescentlamps, said ballast including a core formed from two stacks of E-shaped laminations arranged in abutting relationship to form a shell type core, the cross sectional areas of the legs of one of said stacks being greater than that of the corresponding legs of the other, a lagging secondary winding and a primary winding disposed on the central leg of that stack which is of smaller cross section, and a leading secondary winding disposed on the central leg of the other stack, said windings being spaced from each other in end to end relationship to provide flux leakage paths, and the butt joint between said stacks being opposite the flux leakage path between said primary and said leading secondary windings.

4. A ballast for a fluorescent lamp system embodying two lamp circuits, said ballast comprising a press fit, shell type core having a winding leg portion and a yoke portion, a primary winding centrally disposed on said winding leg portion, a first secondary winding disposed on said winding leg portion at one side of said primary winding, and a second secondary winding disposed at the other end of said winding leg portion, all of said windings being spaced from each other so as to provide for leakage reactance, those parts of said winding leg and yoke portions which are adjacent to said second secondary winding being of greater cross section than the remainder of said core in order to compensate for the increased voltage in said second secondary winding when connected into a leading load circuit.

5. A ballast for a fluorescent lamp system embodying two lamp circuits, a core having a winding leg portion and a yoke portion providing a closed magnetic circuit, a primary winding disposed on said winding leg portion, two secondary windings disposed on said winding leg portion at opposite sides of said primary winding, all of said windings being spaced from each other so as to provide for leakage reactance and being linked by said core, and said secondary windings being proportioned to provide substantially equal starting voltages, those parts of said winding leg portion and said yoke portion which link one of said secondary windings being of greater cross section than the remainder of said core in order to compensate for the increased operating voltage in said last-mentioned secondary winding when connected into a leading load circuit.

LEOPOLD MAUERER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,874,806 Ross Aug. 30, 1932 1,950,394 Boucher Mar. 13, 1934 2,025,471 Osborne Dec. 24, 1935 2,302,571 Ray Nov. 17, 1942 2,402,207 Ranney June 18, 1946 2,404,254 Short July 16, 1946 

